Colloidal plant powder/extract encapsulation with pectin-protein coacervate gels

ABSTRACT

A process for preparing coated particles of a plant material includes: (a) combining plant material particles and a protein in a liquid medium, wherein the protein adsorbs onto at least a portion of a surface of the particles to form a first layer; and (b) mixing a polysaccharide including a pectin with the liquid medium, so that the polysaccharide adsorbs onto at least a portion of a surface of the first layer to form a second layer. In addition, a palatable product comprising at least one coated particle prepared by this process is described.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation application of U.S. application Ser.No. 12/577,058 entitled COLLOIDAL PLANT POWDER/EXTRACT ENCAPSULATIONWITH PECTIN-PROTEIN COACERVATE GELS, filed on Oct. 9, 2009, the entirecontent of which is hereby incorporated by reference.

BACKGROUND

Some users of orally-enjoyed plant material including chewing tobaccoand/or snuff compositions notice certain negative flavor characteristicsassociated with bitterness, astringency, acridness, and/or aftertaste;thus there is perceived a need to overcome these negative tastecharacteristics.

A related disclosure exists in the commonly-assigned U.S. applicationSer. No. 12/155,227 filed on May 30, 2008.

SUMMARY

In one embodiment, a process is provided for preparing coated plantparticles, comprising combining particles of finely-divided plantmaterial with one or more proteins in a liquid medium, under conditionseffective to adsorb the protein onto at least a portion of a surface ofthe particles to form a first layer; and mixing one or morepolysaccharide compositions comprising a pectin with the liquid medium,under conditions effective to adsorb at least some of the pectin onto atleast a portion of a surface of the first layer to form a second layer,thereby forming coated particles of plant material.

In another embodiment, a coated particle of plant material is provided,comprising a base particle of finely-divided plant material; a firstlayer at least partially coating the base particle, the first layercomprising a protein; and a second layer at least partially coating thefirst layer, the second layer comprising a polysaccharide compositionincluding a pectin.

In yet another embodiment, the coated particle is such that (1) the baseparticle has a largest dimension of less than about 3 mm in size; (2)the coated particle comprises (a) plant material in an amount of about10 to about 90% by dry weight, (b) the first layer in an amount of about1% to about 20% by dry weight, and/or (c) the second layer in an amountof about 5% to about 50% by dry weight; (3) the coated particle has amoisture content of less than about 15% by weight; and/or (4) the coatedparticle has a net negative or neutral charge; or a combination thereof.

In a particular embodiment described herein, the finely dividedparticles of plant material can be formed from finely ground tobaccoparticles coated with tobacco-sourced proteins and tobacco-sourcedpolysaccharides, such as tobacco-sourced pectins. This embodiment, byrelying on tobacco sources for certain of the biopolymer coatings,increases the net tobacco content of the product, and thereby provides acost savings resulting from use of tobacco plant products that mightotherwise be wasted.

BRIEF DESCRIPTION OF DRAWINGS

FIGS. 1 a, 1 b, 1 c, and 1 d are Environmental Scanning ElectronMicroscope (ESEM) images of coated tobacco particles prepared accordingto Example 1 herein.

FIGS. 2 a, 2 b, 2 c, 2 d, and 2 e are ESEM images of coated tobaccoparticles prepared according to Example 2 herein.

FIGS. 3 a, 3 b, 3 c, 3 d, 3 e, and 3 f are ESEM images of coated tobaccoparticles prepared according to Example 3 herein.

FIGS. 4 a, 4 b, 4 c, 4 d, and 4 e are ESEM images of coated tobaccoparticles prepared according to Example 4 herein.

FIGS. 5 a, 5 b, 5 c, and 5 d are ESEM images of coated tobacco particlesprepared according to Example 5 herein.

FIGS. 6 a, 6 b, 6 c, 6 d, and 6 e are ESEM images of coated tobaccoparticles prepared according to Example 6 herein.

FIGS. 7 a, 7 b, 7 c, 7 d, and 7 e are ESEM images of coated tobaccoparticles prepared according to Example 10 herein.

DETAILED DESCRIPTION

The present application describes processes for preparing particles ofplant material, in particular ground tobacco particles, coated withpolysaccharide-protein coacervate gels, and in particular withpectin-protein coacervate gels.

It may be advantageous to coat plant materials for use in orallyutilized compositions in order to improve the acceptability of theproduct to the consumer. Such a coating should improve the “mouth feel,”taste, texture, appearance, smell, flavor and/or flavor delivery, orother attributes of the plant material, and thereby make the productmore acceptable to the user.

Plant materials that may be encapsulated include smokeless tobaccos,comprising chewing tobacco, snus, dry snuff, and moist snuff. Some usersof chewing tobacco and/or snuff compositions notice certain negativeflavor characteristics associated with bitterness, astringency,acridness, flavor harshness, and/or aftertaste: thus there is perceiveda need to treat the compositions with a variety of flavors to overcomethe negative taste characteristics sometimes associated with them.

The coated particles described herein are beneficial because thepalatable or comestible products containing them can take a variety ofdifferent forms, including chewable and non-chewable edible forms, suchas in the form of a tablet, stick, strip (which may be more or lessflexible), snus, pouched product, chewable gum, spongy material, orcombinations of these.

Because the coated particles possess a neutral aesthetic color, asopposed to the deep brown color of, e.g., ground tobacco particles, theycan be incorporated into these different products without the need foradded colorants. The coated particles also exhibit reduced odor comparedto, e.g., uncoated tobacco particles. Additionally, a coating asdescribed herein may provide for improved cohesion in the case of aproduct incorporating compressed plant material.

Moreover, when the coated particles are in the mouth, they swell uponmixture with saliva, creating a pleasant mouthfeel, and reducing certainundesired physiological sensations, such as throat itching, that cansometimes be observed when uncoated tobacco products are used. Theparticles provide a mild, creamy flavor and texture that combinesparticularly well with other food ingredients, such as sugars, starches,polyols, oils, lipids, waxes, fats, fatty acids, glycerides, etc.

The coated particles provide relatively slow, controlled release offlavors from the plant material, and provide a means for modifying theflavorant release by control of shell integrity, shell thickness, andgel strength. In a particular embodiment, where the pectins at leastpartially contain those obtained from tobacco materials, economicefficiencies from the use of tobacco-sourced materials are obtained aswell, since they can replace biopolymers that might otherwise result ingreater costs.

As used herein, the term “coacervate” is used in the sense understood bya person skilled in the art, and denotes aggregations of molecules heldtogether via non-covalent interactions such as electrostatic, van derWeals and hydrophobic attractive forces, etc. In a more particularembodiment, the term coacervate is used to denote the aggregation ofmolecules on the surface of one or more particles of plant material,such as tobacco particles, that are held to an aggregation of proteinmolecules (typically electrostatically charged) that form a coating onat least part of the surface and form a first layer. These proteinmolecules in turn are held to an aggregation of polysaccharidemolecules, containing one or more pectins, more particularly containingone or more pectins derived from tobacco plants, that form a coating onat least part of the surface of the first layer, thereby forming asecond layer.

As used herein, the term “particle” denotes a relatively small,subdivided unit of material, which may be in one or more of a variety ofregular or irregular shapes. The term is intended to include powders,granules, shreds, and elongated structures, such as whiskers, fibers,and the like. The term is also intended to include droplets, e.g.,droplets of liquid plant extract.

As used herein, the term “colloidal” is reasonably understood by aperson skilled in the art and may generally mean “having the nature of acolloid.” A “colloid” refers to a system in which finely dividedparticles, which are approximately 10 to 10,000 angstroms in size, aredispersed within a continuous medium in a manner that prevents them frombeing filtered easily or settled rapidly.

As used herein, the term “finely divided” denotes to possess an averagesize of about 3 mm or less. To “finely divide” a material includestreating by comminution, pulverization, grinding, cutting, shredding,and the like, to produce a finely divided material.

As used herein, the term “about” when used in conjunction with a statednumerical value or range has the meaning reasonably ascribed to it by aperson skilled in the art, i.e. denoting somewhat more or somewhat lessthan the stated value or range, to within a range of ±10% of the statedvalue.

Plant Material Particles

Any plant material typically consumed by humans or animals can be coatedby the methods described herein. Particularly suitable plant materialsinclude tobacco and tobacco substitutes. The plant materials aregenerally in particulate form, and are preferably under 3 mm in size,more preferably under 1000 microns in size.

Suitable particles of plant material may include, or be derived from,any part of a plant, such as leaf, stem, flower, fruit, nut, bean, bark,root, and the like. The term “derived from,” as used herein, is intendedto include any materials obtained by processing plant part(s) itself,such as extract fractions of a plant (e.g., an extract of a tobaccoplant) or parts thereof. The particles may be in any suitable formincluding, but not limited to, shreds, granules and powders, and canhave any desired shape, such as different regular and irregular shapes.Suitable regular shapes may include round, square, rectangular, oval,other polygonal shapes, cylindrical, fibrous, and the like.

In one embodiment, the particles of plant material can include ground(including micronized) powders, such as tobacco powders. Preferably, theparticles can have a diameter less than about 3 mm, and more preferablyless than about 1000 microns, and even more preferably, between about0.2 microns and about 250 microns, and most preferably, between about 1microns and about 100 microns. In a further embodiment, the particlescan include ground or micronized particles of sufficient size that theycan form a colloidal suspension of particles in a liquid medium, moreparticularly in an aqueous medium, such as water.

In a particular embodiment, the particles of plant material can beelectrostatically charged, Zwitterionic, or neutral. Electrostaticallycharged particles can more easily attract and hold one or more proteinsto form a coacervate. If the ground plant material does not have thedesired innate charge for attracting the protein coating material, theparticles may be treated to alter the charge thereof before being mixedwith the protein coating material, as described in more detail herein.In a particular embodiment, the particles can desirably have a negativeoverall electrostatic charge. Ground tobacco particles generally have anet negative electrostatic charge if untreated.

Protein

A variety of proteins can be used to form the coacervate describedherein. Examples of suitable proteins include proteins from animal orplant sources, such as milk proteins, whey proteins, rice proteins,wheat proteins, soy proteins, corn proteins, egg white proteins, proteinfractions from tobacco or tobacco extracts, fish protein, gelatins,protein hydrolyzates, and the like. Examples of suitable gelatins mayinclude, but are not limited to, fish gelatin, beef gelatin, porkgelatin, and gelatin hydrolyzates. These proteins may be usedindividually or in combinations thereof. In a preferred embodiment, theprotein includes a protein obtained from a tobacco source, such asextracted tobacco plant material, or a tobacco extract.

Desirably, the protein is rich in the amino acids lysine, asparagine,glutamine, and/or arginine.

In a particular embodiment, the protein desirably has a molecular weightranging between about 2 KDaltons and about 1000 KDaltons, andpreferably, between about 15 KDaltons and about 500 KDaltons.

The protein coating material can have an overall electrostatic charge,or can be Zwitterionic or neutral. It is desirable to select a proteincoating material that has an electrostatic charge that will be attractedto, and will attract, the charge possessed by the tobacco particles.Charges on the protein can also facilitate electrostatic complexationbetween the protein-coated particle and a subsequent polysaccharidecoating, thereby helping to form the coacervate. In one embodiment, theprotein coating material can be Zwitterionic or cationic in the casewhere the tobacco material has an overall negative electrostatic charge.The electrostatic charge on the protein can be modified by placing theprotein in an aqueous solution, and adjusting the pH of the solutionuntil the desired charge is obtained. The pH adjustment necessary andthe resulting electrostatic charge obtained depend, to some extent, onthe pKa of the protein side chains. For example, acidifying the proteinsolution (so that pH<pKa of the acidic and basic side chains) willgenerally place a net positive electrostatic charge on the protein,while making the protein solution more alkaline (pH>pKa of the acidicand basic side chains) will generally result in proteins having a netnegative electrostatic charge.

Polysaccharide

The term “polysaccharide,” as used herein, is intended to include apolysaccharide, an oligosaccharide or a mixture of these, which can forma coacervate with a protein. In a particular embodiment, thepolysaccharide includes one or more pectins. Other materials that can bepresent in the polysaccharide composition in addition to pectin includechitosan, modified cationic polysaccharides, amidated pectins, andamidated starches containing amino groups, carrageenans, alginates,gums, such as gellan gum, gum Arabic, gum tragacanth, locust bean gum,or xanthan gum, carboxymethylcellulose, anionically modified starches orcelluosic materials containing carboxy groups, nonionic agar, orcurdlans.

Pectins are relatively high molecular weight polyuronide substancesfound naturally in varying concentrations in fruit or plants, andconsisting chiefly of partially methoxylated galacturonic acids linkedtogether to form long chains. Pectins are often obtained in the form ofsolid powders or concentrated syrups, and are capable of gelation atroom temperature. They are generally soluble in water and insoluble inmost organic solvents. Pectins are often obtained by dilute acidextraction of plant material, in particular from the rind of fruits,such as citrus fruits, or from fruit pomace, which is the solid remainsof fruit (which may include pulp, peel, seeds, and stalks) afterpressing for juice.

Examples of suitable pectins may include, but are not limited to,pectins from tobacco sources, apple pomace, citrus peel, plums, orgooseberries, or combinations of these. Preferably, the pectin includesa pectin from a tobacco source. Pectins can form coacervates with theproteins forming the first layer of coating on the particle without theneed for the addition of salts.

The polysaccharide composition forms a second layer of the coating ofthe particle by forming a coacervate with the protein contained in thefirst layer. If this second layer is the outermost coating layer, thepolysaccharide composition should be chosen so as to optimize itsswelling behavior and visco-elasticity under physiological pH andtemperature conditions, in order to control the kinetics of extractionfrom the particulate plant material. The coated particle should alsoremain stably coated for a time generally ranging from about 10 minutesto 20 minutes when exposed to saliva.

Control of the kinetics of extraction can be exercised primarily bymanipulating the gel strength of the polysaccharide. Gel strength can becontrolled by, e.g., controlling the molecular weight, polydispersity,degree of esterification, degree of pectin amidation (in particular, thedegree of amidation of tobacco-derived pectins), combining pectins withcarageenans, and/or by manipulating the processing of the coatedparticles, and in particular, the order of addition of polysaccharidesand/or proteins.

In a particular embodiment, the suitable polysaccharide generally have amolecular weight ranging between about 5 KDaltons and about 1,000KDaltons, preferably between about 100 KDaltons and about 500 KDaltons,and more preferably, between about 200 KDaltons and about 500 KDaltons.Preferably, the polysaccharide used as a coating material should besubstantially free of salts, sugars or hemicelluloses, (e.g., compoundswith a molecular weight of between about 1 KDaltons to about 5KDaltons), and should be non-standardized (i.e., supplied in a formwithout additives).

The polysaccharide coating material can be ionic, Zwitterionic, orneutral. In one embodiment, the polysaccharide coating material can beZwitterionic or anionic. A polysaccharide having a net negativeelectrostatic charge is desirable because it forms a stable coacervatewith a positively charged protein layer. The charge on thepolysaccharide, if desired, can be manipulated by, for example,adjusting the pH of the liquid medium containing the polysaccharide.

Additional polysaccharides may also be included in the polysaccharidecomposition. These can include materials such as anionic gellingpolysaccharides, such as other pectins and carrageenans, and/or caninclude nonionic gelling polysaccharides, such as curdlan, agar, and/orlocust bean gum. Other polysaccharides that can be included are one ormore of gum arabic, carboxymethyl cellulose (CMC), sodium alginates, gumtragacanth, gellan gum, xanthan gum, and combinations of these.Additional polysaccharides, which preferably include a carrageenan, morepreferably, a κ-carageenan, can be added in the form of an outerpolysaccharide layer disposed on top of a pectin layer, or can form partof the pectin layer itself. In either case, the strength of the coatinglayer (and its coating efficiency) can be modified by introducing, e.g.,a κ-carageenan into the coating materials in an amount ranging betweenabout 10 wt % and about 60 wt %, based on the total polysaccharide inthe first and second layers. Addition of such polysaccharides canprovide control over the kinetics of release of flavors from the plantmaterial particles by providing better gel strength, and by improvingencapsulation efficiency.

Physical properties of several types of pectin suitable for use hereinas the polysaccharide are provided in Table 1 below.

TABLE 1 Physical Property Data for Pectins Intrinsic Huggins SolventPectin Description viscosity (dl/g) coefficient conditions pH MW Sigmaapple 6% ester, low 5.8556 0.0643 Good 3.389 613,740 pectin ester pectindraining Genu Pectin Amidated low 4.9261 0.8462 Poor 2.984 479,760 TypeX-916- ester pectin, solvent 02 17% conditions amidation, 34% ester, nosugar Genu Pectin Around 40% 3.6156 0.827 Poor, non- 3.052 376,300 TypeLM 18- ester, no draining CG-Z sugar Tobacco Very low 1.881 0.4154 Verygood 2.983 259,530 pectin ester pectin draining (unwashed) Tobacco Verylow 1.3514 0.02749 Very good 4.420 237,270 pectin ester pectin draining(dialyzed)

Among the above pectins, gel strength in a protein-pectin coacervate hasbeen found to generally decrease in the order Genu Pectin Type LM18-CG-Z>Genu Pectin Type X-916-02>Sigma apple pectin>Tobacco pectin.Increased molecular weight and an ester content of about 30 to 40% arebelieved to help promote a strong gel network, in the absence of salt asa crosslinking agent. Network formation in the coacervate is believed tobe favored by interactions between the amino groups of the protein andcarboxylic groups of the pectins.

Moreover, the polymer-solvent interactions of the above pectins havebeen found to be significantly different from each other, as indicatedby the difference in Huggins coefficients. These differences may beattributable to the degree of branching of the pectins, as well as thelevels of esterification and/or amidation. A Huggins coefficient ofbetween about 0.6 and 0.9, preferably about 0.8, has been found to beparticularly desirable for pectin-protein coacervate gel formation.

Coating Process

In one embodiment, particles of plant materials, such as tobaccoparticles, and a protein can be combined by combining the particles, ora colloidal dispersion of the particles in a dispersing medium, with adispersion or solution of the protein coating material to form a firstmixture. In a particular embodiment, the dispersing medium can be anaqueous medium containing water, and in a more particular embodiment, isdeionized water. In a particular embodiment, the protein content in theliquid medium may be about 0.5% to about 2% by weight, based on thetotal weight of the resulting mixture.

The particles of plant material are typically naturallynegatively-charged. However, if the particles are not negatively-chargedas obtained, they may be treated with appropriate reagents to impart anegative charge to the particles before they are mixed with the proteincoating material. For example, particles may be treated with anappropriate amount of one or more bases such as sodium carbonate, sodiumbicarbonate, and/or sodium hydroxide (such as lye), to impart a negativecharge to at least some of the particle surfaces.

Desirably, the surface of the uncoated particles attracts protein, viaelectrostatic attraction, for example. The protein deposits onto atleast a portion of a surface of the particles, thereby forming a firstlayer of a coating. Preferably, the protein forms a layer substantiallycovering the entire surface of at least some of the particles, anddesirably of the majority, or substantially all, of the particles. Thethickness of this first layer may be uniform or non-uniform.

The net electrostatic charge of the protein, if desired, can bemanipulated by, for example, adjusting the pH value of a liquid mediumin which the protein is suspended or dissolved. This can aid indeposition of the protein onto the particle surface, as described above.In one embodiment, materials can be added to lower the pH of the liquidmedium containing the protein, thereby imparting a positive charge onthe protein. Suitable pH lowering materials include weak organic acids,such as acetic acid, adipic acid, fumaric acid, malic acid, lactic acid,tartaric acid, or gluconic acid and glucono delta lactone, strong foodgrade hydrochloric acid, and mixtures of these. In a particularembodiment, food-grade materials are used to adjust pH. In anotherembodiment, a positively charged protein can be prepared by coating asolid protein material with one or more of the acids mentioned above.

Once a coacervate has formed between the particles of plant material andthe protein, the resulting protein-coated particles can then becontacted with a polysaccharide composition, either by adding thepolysaccharide to the protein-coated particles, or by adding theprotein-coated plant particles to the polysaccharide coating material.

In embodiments where the polysaccharide is added to the protein-coatedparticles, or where the protein-coated plant particles are added to thepolysaccharide, the overall electrical charge of the protein coating onthe plant particles can be altered by adjusting the pH of the liquidmedium prior to mixing of the protein-coated particles with thepolysaccharide coating material. Suitable substances for adjusting thepH may include either acids and bases, e.g., weak organic acids such asacetic acid, adipic acid, fumaric acid, malic acid, lactic acid,tartaric acid, gluconic acids and glucono delta lactone or stronginorganic acids, such as food grade hydrochloric acid, or bases such assodium carbonate, sodium bicarbonate or sodium hydroxide. In oneembodiment, the protein coating can be treated with an acid to impart apositive charge to at least some of the surface of the protein coating,thereby facilitating electrostatic attraction of the polysaccharidecoating material. For example, the pH of the first mixture containingthe protein-coated plant particles may be adjusted to about 3.5 to about6.0 with an acid, such as citric acid, although the precise acid usedand amount of pH adjustment obtained will depend to some extent on theprotein used.

In an embodiment, the polysaccharide composition may be mixed with theprotein and with uncoated particles in the form of a suspension orsolution. Because of the respective electrostatic attractions andrepulsions, the protein can deposit onto at least a portion of thesurface of the particles and the polysaccharide can deposit onto atleast a portion of a surface of the deposited protein, thereby form atwo-layer coating.

In any of the embodiments described herein, the thickness of the proteinand/or polysaccharide coating may be uniform or non-uniform. Preferably,the polysaccharide forms a layer substantially covering the entiresurface of the protein coating on the particles.

As indicated above, the polysaccharide desirably contains at least onepectin. The pectin can form a complex coacervate layer with the proteinas a result of hydrophobic interactions and/or electrostaticcomplexation, in the presence or in the absence of a salt, which canhelp to crosslink the pectin layer, forming the pectin coating into agel.

Alternatively, or in addition, the proteins in the first coating layerand/or the polysaccharides of the second coating layer can gel as aresult of hydrogen bonding, hydrophobic interactions, electrostaticinteractions, formation of salt bridges (e.g., monvalent, divalent, ortrivalent cation-induced crosslinking resulting from the addition of,e.g., potassium, calcium, magnesium, and/or iron salts of chloride,citrate, lactate, acetates, and/or other counterions), van der Waalsinteractions under room temperature or below, or during hot processingconditions, or some combination of these.

Gelation may be induced by various methods, such as adjusting the pH ofthe liquid medium containing the particles; adding monovalent, divalentor trivalent cations to the liquid medium containing the particles(which, at the time of addition, may be uncoated, coated with protein,or coated with protein and polysaccharide); heating the particles to atemperature of between about 60° C. and about 90° C. for about 1 toabout 3 hours; cooling the particles to a temperature of between about20° C. and about 0° C. for about 1 to about 48 hours; removing at leastpart of the liquid medium from the coated particles by drying, e.g., byspray drying, freeze drying; or combinations of these procedures.

In a particular embodiment, a salt may be included along with theprotein and/or the polysaccharide composition at least in part tofurther assist in formation and gelation of a coacervate layer from thepectin-containing polysaccharides and the protein. Examples of suitablesalts may include, but are not limited to, monovalent, divalent ortrivalent cations such as potassium, calcium, magnesium and iron, in theform of salts such as chloride, citrate, lactate or acetate salts. Thesesalts may be used individually or in combination thereof. In aparticular embodiment, a divalent salt, such as salts of calcium andmagnesium, can be introduced during or after the addition of thepolysaccharide composition to the particles. The resulting coatedparticle may have a net negative or neutral charge.

However, it has been found that the addition of such a salt is notnecessary in order for gel formation to occur when a polysaccharide suchas pectin is added to a protein layer. More specifically, gel formationis facilitated by specific interactions, believed to be betweencarboxylic groups of the polysaccharide and amino groups of the proteins(or between amino groups of the polysaccharide and carboxylic groups ofthe proteins). This is particularly true under processing conditions of60-90 ° C. for 1-3 hours. The result of these interactions is that apolysaccharide-protein coacervate (and in particular, a pectin-proteincoacervate) may gel without the addition of divalent metal cations,which have been expected to be necessary for pectin gelation. Theseinteractions allow the gel strength of a pectin-protein coacervate to bemodified and controlled by, e.g., varying the number of availablecarboxylic groups and/or amine groups of the pectin, depending upon thenumber of carboxyl groups or amine groups in the protein able tointeract with them. This can be done by amidation or deamidation ofcarboxyl groups of the pectin, which can convert carboxyl groups tocarboxamides, or the converse, respectively.

In a preferred embodiment, at least one of the polysaccharides can forma gel in the pH range between about 3 and about 9. Alternatively, or inaddition, at least one of the polysaccharides can form a gel uponaddition of monovalent, divalent or trivalent cations to the liquidmedium during or after addition of the polysaccharide. Cations can beselected from the group consisting of potassium, calcium, magnesium,and/or iron, and can be introduced as chloride, citrate, lactate, and/oracetate salts that are added to the liquid medium during or afteraddition of the polysaccharides coating material to induce formation ofthe gel, e.g., via formation of salt bridges. As described herein,gelation may also be induced or aided by heating (e.g., to a temperaturebetween about 60° C. and about 90° C., and preferably, between about 60°C. and about 80° C., for about 10 to about 180 minutes, and preferably,for about 60 to about 90 minutes). In particular, the use of, at leastin part, commercially available pectins can reduce or eliminate the needfor the addition of a salt, since such commercial pectins tend to gelimmediately upon heating.

After formation, the gel may desirably be stabilized by cooling ormaintaining it at a temperature below the temperature of gel formation,and preferably below room temperature, but above the freezing point ofthe gel, and typically between about 20° C. and about 0° C., andpreferably, between about 15° C. and about 5° C., for about 1 to about60 hours, and preferably, about 12 to about 48 hours.

It may also be advantageous to add one or more additional components orother additives during the processing to affect the “mouth feel,” taste,texture, appearance, smell, flavor and flavor delivery and otherattributes of the coated particles. These components may include, butare not limited to, the following: gum arabic, flavorants, colorants,sweeteners, such as xylitol, bulking agents, fillers, anti-adherentcompounds, dispersing agents, moisture absorbing compounds, chemestheticagents, such as warming agents or cooling agents, and film-formingagents. Other food ingredients, such as starches, polyols, oils, lipids,waxes, fats, fatty acids, glycerides, etc., may be also added to thecoating to enhance the mouth-feel of the finished, dried product.Additives, such as flavorants, chemesthetic agents, throat-soothingagents, spices, warming agents, tooth-whitening agents,breath-freshening agents, vitamins, minerals, caffeine, drugs, and otheractives may be included in any or all layers or portions of thecoatings. Such components may be used in amounts sufficient to achievetheir intended effects.

The process of forming the protein-polysaccharide coacervate coating, orsteps thereof, may be repeated, if desired, by using the same ordifferent coating materials as those described for the protein andpolysaccharide coating materials, with or without the above-mentionedadditional components or additives. A series of layers can therefore bebuilt up around the particle of plant material, each of which may be thesame or different from other layers, and which may provide desirableproperties, such as varying flavorant or chemesthetic effect, to theuser as the various layers of the coating come into contact with saliva.

By using the methods disclosed herein, the strength of the coatinglayers of the particles of plant materials described herein, and thus,the coating efficiency, can be controlled to achieve the desired releasekinetics of flavorant from the plant material. In a particularembodiment, at least one of the polysaccharides in the second coatingcan form a gel in the pH range of about 3 to about 9. In thisembodiment, additional gel formation in the second coating layer mayfurther improve the coating strength. For instance, κ-carrageenan canform a relatively strong and rigid gel under similar pH conditions, andmay be included in the polysaccharide coating material. The amount ofκ-carrageenan, which is preferably incorporated in the coated particlesin the range of about 10% to about 60% be weight, based on the totalweight of the polysaccharides in the coated particles.

The strength of the coating on the particles may also be manipulated bymodifying the above-described coating process. In particular, theoutermost layer may be preferentially optimized in terms of the swellingbehavior and visco-elasticity under physiological pH and temperatureconditions, for controlling the extraction kinetics of materials fromthe coated particles.

In one embodiment of a method for making the coated particles of plantmaterial described herein, a protein is added to particles of plantmaterial in a liquid medium, forming a first layer thereon. This firstlayer can form on at least on a portion of a surface of the particles,and preferably substantially cover the entirely surface of theparticles. Thereafter, a pectin can be to the protein-coated particlesobtained in the first step. The added pectin can be adsorbed onto atleast a portion of, and preferably all of, the surface of the firstlayer, to form a second layer. Preferably, this second coating layersubstantially covers the entire surfaces of the first coating layer. Atthis stage, the pectin in the second coating layer may interact with theprotein in the first coating layer, thereby forming coacervate. Further,κ-carrageenan can be added to the double coated particles and adsorbonto at least a portion of a surface of the second layer to form a thirdlayer. Preferably, this third coating layer substantially covers theentire surfaces of the second coating layer. The thickness of theκ-carrageenan coating may be uniform or non-uniform. At this stage,κ-carrageenan in the third coating layer may form a gel underappropriate conditions, thereby forming the outermost relatively stronggel layer.

In a particular embodiment, the protein and polysaccharide compositioncan, if desired, be added to the particles of plant materialsimultaneously in a liquid medium. Because of the coacervationmechanism, the protein will preferentially form a first layer on thesurface of the particles of plant material, while the polysaccharidewill preferentially form a second layer on the protein layer.

Upon completion of the coating procedures, the mixture containing thecoated particles may optionally be homogenized or otherwise processed.Following any such optional processing, the coated particles may then bedried to provide a material that comprises individual dried particles,or agglomerations of particles. Prior to, or as part of, the dryingprocess, the liquid content of the mixture may be adjusted, e.g. to byremoving large quantities of liquid, or by adding liquid. If the liquidis to be removed or reduced, it may be separated by customary means,such as decanting and filtering. Alternatively, if water and preferablydeionized water may be added to the mixture to achieve the desiredconsistency for spray drying or freeze drying. For example, the finalsuspension may contain about 2 wt % of solids based on the total weightof the mixture.

If spray drying is utilized, for example, the suspension of coatedparticles can be atomized from a liquid feed into a spray of droplets,wherein the droplets can be placed in contact with drying air to formdry coated particles. As an alternative to spray drying, the coatedparticles can be passed through a tunnel drier at about 90° C. to about95° C. to flash off a majority of the liquid, then air dried at roomtemperature to form final particles.

In a particular embodiment, the coated particles can desirably be driedto a moisture content of less than about 15%, preferably, about 2% toabout 10%, and more preferably, about 2% to about 6%. Drying may becarried out by any suitable method, such as spraying drying,freeze-drying, fluidized bed drying, and vacuum-drying.

In a more particular embodiment, the method for making the coatedparticles described herein comprises: (a) dispersing a protein, which ispositively charged, and particles of a plant material, such as atobacco-containing powder, which is negatively charged, in an aqueousliquid, wherein the protein adsorbs onto the surfaces of the negativelycharged particles; (b) adjusting the pH of the mixture of protein-coatedparticles and aqueous liquid to enhance the positive charge on thesurface of the protein, and to promote complexation between thepositively charged protein and the negatively charged polysaccharide inthe next layer; (c) mixing of a polysaccharide composition, in the formof a solid, or solution, or both, in the aqueous liquid containing theprotein-coated particles, heating this mixture to a temperature of about60° C. to about 90° C. to dissolve the polysaccharide and promoteinteractions between the polysaccharide and protein; (d) optionallyadding salts, such as potassium or calcium lactate, or other polyvalentmetal salts, to act as crosslinking agents that promote gelation of thepolysaccharide shell; (e) cooling the resulting mixture for about 24 toabout 48 hours to promote gel formation via hydrogen bonding; and (f)removing water by, e.g., spray drying, freeze drying, or fluidized beddrying.

In certain embodiments, the final composition of the coated particlesmay contain, as weight percents based upon the dry weight of coatedparticles, about 10% to about 90% of plant material, more particularlyabout 20% to about 80%, and more particularly, about 40% to about 70%plant material. The first coating may comprise an amount of the coatedparticle ranging from about 1% to about 20%, more particularly about 1%to about 30%, even more particularly about 5% to about 15%, by weightbased on the total dry weight of the coated particles. The secondcoating may comprise an amount of the coated particle ranging from about1% to about 60%, more particularly about 15% to about 50%, even moreparticularly about 15 to about 40%, by weight based on the total weightof the coated particles.

The particle size of the particles, if they spray dried, can be anywherefrom about 0.20 micron to about 4000 microns, preferably between 0.25micron to about 1000 microns, more preferably between 0.3 micron and 250microns, and even more preferably between 0.3 micron and 100 microns. Ina particular embodiment, the coated particles include colloidal coatedparticles, and in particular, colloidal coated tobacco particles.

The processes described herein may also be used to coat selectivecomponents on droplets of an extract of a plant material, such as atobacco extract liquid, to prepare coated particles which areessentially encapsulated droplets. In particular, the particles whichcan attract the coating materials will be selectively coated.Conversely, the particles which expel the coating materials may not becoated and thus remain in the liquid in their original form.

The coated particles, and in particular, coated tobacco particles,described herein may preferably have a net negative charge and a zetapotential value of about −5 mV to about −60 mV, more particularly fromabout to about −15 mV to about −40 mV, to prevent excessiveagglomeration of particles and a gritty texture.

Once dried, the coated particles may be easily incorporated into avariety of different palatable or edible products. These palatable oredible products can take the form of a tablet, stick, chewable gum,spongy material, foam, cream, pelleted material, or fiber, or a formsuitable to be contained in a pouch, or combinations of these. Examplesof such palatable or edible products include chewable or non-chewableedible forms, including tablets, candies, gums, chocolates, flavoredsponges, and the like.

The coated particles described herein can have a color lighter than thatof the uncoated plant material. For example, coated tobacco particlescan have a light beige color, which is lighter than the dark brownishcolor of raw tobacco materials, making the coated particles moreaesthetically suitable for inclusion in neutral-colored edible systems.

Upon swelling and/or hydration, the coated particles may form asuspension of plant particles in the mouth, which can create a pleasantin-mouth feel, optionally in the presence of other food ingredients suchas sugars, starches, polyols, oils, lipids, waxes, fats, fatty acids,glycerides, etc.

The release of selected compounds from the coated particles describedherein may be triggered by simple diffusion into saliva, or may occurupon application of pressure by the tongue and/or teeth to theparticles. For example, upon ordinary chewing or dipping of the product,the user will release flavorings or other attributes as hydrationoccurs. In the presence of the enzymes in the saliva, the pectin-proteincoatings on the particles may be stable for a limited period of time,for example, about 10 minutes to about 20 minutes.

The time that the coating is stable in the mouth may be changed byselection of particular proteins/polysaccharides in the coatings and bymodifying the other aspects of the coacervation process that affect gelstrength, as described above. The extraction mechanics of the particles(for example, extraction of tobacco flavor) in the mouth may be alteredby altering one or more of the following characteristics of thecoatings: swelling behavior, visco-elasticity under physiological pH andtemperature conditions, porosity, stability or rate of diffusion ofingredients under application of pressure by tongue or teeth or both,stability from dissolution upon attack from the enzymes in saliva, orcombinations of these.

In addition, one or more of the following characteristics of thecoatings can be optimized for controlling the mouth feel of the edibleproduct: slipperiness, sliminess, firmness, sponginess, stability orrate of diffusion of ingredients under application of pressure by tongueor teeth or both, stability from dissolution upon attack from enzymes insaliva, or combinations of these. These properties can be varied byselecting different coating materials for the first and second coatingmaterials, combining different coating materials, modifying theproperties of coating materials, e.g., by crosslinking, or combinationsof these.

The following Examples are provided to increase understanding of theprocesses and products described herein, and are not intended to limitthe scope of the appended claims. Mean particle size is measured by wetstate Horiba LA 910 light scattering. ESEM images are obtained byplacing a sample of particles onto 12 mm diameter carbon adhesive disksattached to Al stubs, sputter coated with 20 nm of Au—Pd using aCressington 208 HR Sputter Coater operating in Ar, and imaged using anFEI XL30 Environmental Scanning Electron Microscope operating at 15 kVin Hi-Vac mode.

EXAMPLE 1

A gelatin/pectin coacervate gel encapsulated tobacco powder was preparedby dispersing in 91 g of deionized water 0.91 g of gelatin from porcineskin, type A, 300 Bloom as the protein, using a high shear Silversonmixer. 6.37 g of 400 mesh pasteurized ground burley tobacco was thendispersed into the gelatin mixture using the high shear mixer. 1.54 g of0.5 M citric acid solution (Sigma, 99% pure) was then added to adjustthe pH of the mixture to 4.2. 1.82 g of citrus peel pectin, 40% ester(CP Kelco Genu pectin LM-18-CG) as the polysaccharide was added slowlyto deionized water heated to a temperature of 70-85° C. with continuousstirring, until all of the pectin was dissolved. The resulting viscouspectin solution was then added to the gelatin-tobacco dispersion underhigh shear over 20 minutes. The temperature of the dispersion wasallowed to equilibrate with a water bath at 70-90° C. for 1-3 hours. 3 gof 0.153 M calcium lactate solution (Sigma, 90%) was then added, and theresulting dispersion was removed from the water bath and refrigeratedfor 24 hours. The resulting gel dispersion was homogenized withdeionized water, and then spray dried using a spray drier having aninlet temperature of 200° C. and an outlet temperature of 110° C. Theresulting encapsulated particles were collected in a sample collector,and were found to have a mean particle size of 35.973 μm. ESEM images ofthe coated particles at scales ranging from 350× to 3500× are shown inFIGS. 1 a, 1 b, 1 c, 1 d, 1 e.

EXAMPLE 2

A Na-caseinate/pectin coacervate gel encapsulated tobacco powder wasproduced by following the procedures described above in Example 1, withthe following variations. 0.9 g of low fat Na-caseinate (from AmericanCasein company) was used as the protein instead of gelatin. 6.4 g of 400mesh pasteurized ground burley tobacco were used. 7.24 g of 0.5 M citricacid solution (Sigma, 99% pure) was used to adjust pH. 1.8 g of applepectin, 6% ester (Sigma) was used as the polysaccharide. Calcium lactatewas not added. The resulting sample was designated Sample 17-7B in Table2 below. The coated particles were found to have a mean particle size of42.419 μm, and are illustrated in the ESEM images of FIGS. 2 a, 2 b, 2c, 2 d, and 2 e, with magnifications of 638× to 3038×.

EXAMPLE 3

A Na-caseinate/pectin coacervate gel encapsulated tobacco powder wasprepared by following the procedures described above for Example 2, withthe following variations. 0.91 g of low fat Na-caseinate (from AmericanCasein company) was used as the protein. 7.2 g of 0.5 M citric acidsolution (Sigma, 99% pure) was used to adjust pH. 1.82 g of amidated lowester pectin (Genu pectin X-916-02 from CP Kelco, non-standardized) wasused as the polysaccharide. The resulting sample was designated Sample17-35 in Table 2 below. The coated particles were found to have a meanparticle size of 70.925 μm, and are illustrated in the ESEM images ofFIGS. 3 a, 3 b, 3 c, 3 d, 3 e, and 3 f, with magnifications of 150× to2500×.

EXAMPLE 4

A Na-caseinate/pectin coacervate gel encapsulated tobacco powder wasprepared by following the procedures described above for Example 3, withthe following variations. 1.82 g of low ester (about 40%) pectin (Genupectin LM18 CG-Z from CP Kelco, non-standardized) was used as thepolysaccharide. The resulting sample was designated Sample 17-36 inTable 2 below. The coated particles were found to have a mean particlesize of 45.777 μm, and are illustrated in the ESEM images of FIGS. 4 a,4 b, 4 c, 4 d, and 4 e, with magnifications of 150× to 800×.

EXAMPLE 5

A soy isolate/pectin coacervate gel encapsulated tobacco powder wasprepared by following the procedures described above for Example 2, withthe following variations. 0.91 g of soy isolate (Solae company, Supro EX38) was used as the protein. 7 g of 0.5 M citric acid solution (Sigma,99% pure) was used as to adjust pH. 1.82 g of apple pectin, 6% ester(Sigma) was used as the polysaccharide. The resulting sample wasdesignated Sample 17-25 in Table 2 below. The coated particles werefound to have a mean particle size of 32.974 μm, and are illustrated inthe ESEM images of FIGS. 5 a, 5 b, 5 c, and 5 d, with magnifications of250× to 1500×.

EXAMPLE 6

A lysozyme/pectin coacervate gel encapsulated tobacco powder wasprepared by following the procedures described above for Example 2, withthe following variations. 0.91 g of lysozyme from chicken egg white(Sigma, 99%) was used as the protein. 5.24 g of 0.5 M citric acidsolution (Sigma, 99% pure) was used to adjust pH to 5.2. 1.82 g of applepectin, 6% ester (Sigma) was used as the polysaccharide. The resultingsample was designated Sample 17-13 in Table 2 below. The coatedparticles were found to have a mean particle size of 76.89 μm, and areillustrated in ESEM images at scales ranging from 1000× to 5000× inFIGS. 6 a, 6 b, 6 c, 6 d, and 6 e, where FIG. 6 e is a magnification ofthe portion of FIG. 6 d marked by a box.

EXAMPLE 7

An ovalbumin/pectin coacervate gel encapsulated tobacco powder wasprepared by following the procedures described above for Example 2, withthe following variations. 0.91 g of ovalbumin from chicken egg white(Sigma, 99%) was used as the protein. 7.49 g of 0.5 M citric acidsolution (Sigma, 99% pure) was used to adjust pH. 1.82 g of applepectin, 6% ester (Sigma) was used as the polysaccharide. The resultingsample was designated Sample 17-15 in Table 2 below.

EXAMPLE 8

A beta-lactoglobulin/pectin coacervate gel encapsulated tobacco powderwas prepared by following the procedures described above for Example 2,with the following variations. 0.91 g of beta-lactoglobulin (Davisco)was used as the protein. 7.53 g of 0.5 M citric acid solution (Sigma,99% pure) was used to adjust pH. 1.82 g of apple pectin, 6% ester(Sigma) was used as the polysaccharide. The resulting sample wasdesignated Sample 17-17 in Table 2 below.

EXAMPLE 9

A whey protein isolate/pectin coacervate gel encapsulated tobacco powderwas prepared by following the procedures described above for Example 2,with the following variations. 0.91 g of whey protein isolate (Bi Pro JE365-5-420, Davisco) was used as the protein. 9.1 g of 0.5 M citric acidsolution (Sigma, 99% pure) was used to adjust pH. 1.82 g of applepectin, 6% ester (Sigma) was used as the polysaccharide. The resultingsample was designated Sample 17-31 in Table 2 below.

EXAMPLE 10

A soy isolate/pectin coacervate gel encapsulated tobacco powder wasprepared by following the procedures described above for Example 1, withthe following variations. 0.91 g of soy isolate (Solae company, Supro EX38) was used as the protein. 6.5 g of 0.5 M citric acid solution (Sigma,99% pure) was used to adjust pH. 1.87 g of tobacco sourced pectin(undialyzed) was used as the polysaccharide. 2.77 g of 0.153 M calciumlactate solution (Sigma, 90%) was added. The resulting sample wasdesignated Sample 17-49 in Table 2 below. The coated particles werefound to have a mean particle size of 42.873 μm, and are illustrated inthe ESEM images at scales ranging from 1000× to 5000× in FIGS. 7 a, 7 b,7 c, 7 d, and 7 e.

EXAMPLE 11

A soy isolate/pectin coacervate gel encapsulated tobacco powder wasprepared by following the procedures described above for Example 1, withthe following variations. 0.91 g of soy isolate (Solae company, Supro EX38) was used as the protein. 3.3 g of 0.5 M Citric acid solution (Sigma,99% pure) was used to adjust pH. 1.87 g of tobacco sourced pectin(dialyzed and freeze dried) was used as the polysaccharide. 2.77 g of0.153 M calcium lactate solution (Sigma, 90%) was used as in Example 1.The resulting sample was designated Sample 17-39 in Table 2 below.

EXAMPLE 12

A tobacco sourced protein/pectin coacervate gel encapsulated tobaccopowder was prepared by following the procedures described above forExample 1, with the following variations. 0.86 g of tobacco sourcedprotein (Philip Morris Company) was dispersed into 86.13 g of deionizedwater. 6.10 g of 400 mesh ground burley tobacco was used as the tobaccoparticles. 5.17 g of 0.5 M citric acid solution (Sigma, 99% pure) wasused to adjust pH to 4.2. 1.74 g of 40% ester pectin (Genu pectinLM-18-CG-Z) was used as the polysaccharide.

COMPARATIVE EXAMPLE 1

A soy isolate/x-carrageenan coacervate gel encapsulated tobacco powderwas prepared by following the procedures described above for Example 1,with the following variations. 0.91 g of a soy isolate (Solae company,Supro EX-38) was used as the protein. 9.02 g of a 0.5 M citric acidsolution (Sigma, 99% pure) was used to adjust the pH to 4.2. 1.82 g ofκ-carrageenan (FMC Biopolymers Gelcarin 911 NF) was used as thepolysaccharide. 0.32 g of 0.153 M calcium lactate solution (Sigma, 90%)was used as a crosslinking agent.

The above process may be varied slightly by adding the κ-carrageenanpowder directly into the batch, mixing well, and then equilibrating inthe water bath for 1-3 hours at 60° C.-90° C. to solubilize theκ-carrageenan and facilitate specific interactions and ioniccrosslinking among the carrageenan and protein molecules. Thiseliminates an extra step of making the carrageenan solution separately,which was extremely viscous and was difficult to handle.

The resulting sample was designate Sample 17-92 in Table 2 and Table 3below.

Samples of material obtained from several of the examples describedabove were tested in order to evaluate the rheological properties of thegels using an AR 1000-N rheometer from TA Instruments. During thistesting, a linear visco-elastic region was first established conductingthe strain sweep at 1 Hz. A frequency sweep was then performed at 0.1%strain. Because all of the gels were visco-elastic, their shear moduluswas a complex modulus G*, which contained contribution from a storage orelastic component G′, which represents the strength of the gel network,and a loss or viscous modulus G″, which represents the liquid-likeproperties of the gel. G* can be related to these contributions by theformula:

G* ² =G′ ² +G″ ²

In addition, the ratio of the loss modulus component and the storagemodulus component can be represented by the parameter δ, wherein:

δ=tan⁻¹(G″/G′)

Preferably, δ ranges from about 5 to about 11. More preferably, δ isbetween from about 6 to about 10.

Higher values of G′ indicate a stronger, firmer gel network, and aresults in a lower loss ratio, δ. Conversely, lower values of G′indicate a softer gel. Preferably, G′ ranges from about 10,000 Pa toabout 35,000 Pa.

TABLE 2 Rheological data on protein-carbohydrate coacervate gels at 1Hz, 0.1% strain Sample G′ G″ δ = tan⁻¹ Salt visual # Pa Pa G″/G′ addedobservations protein carbohydrate 17-92 33770 2993.3 5.063 0.32 g firmgel, can Soy isolate κ-carrageenan calcium be cut (Supro Ex 38) lactate17-7B 10570 1281 6.909 none solid gel, easily Na-caseinate Sigma applesliceable pectin 17-25 13530 2504 10.48 none hard gel, Soy isolate Sigmaapple firmest of all (Supro Ex 38) pectin 17-35 17390 2380 7.79 nonemedium firm Na-caseinate Genu Pectin gel Type X-916-02 17-36 24400 38899.056 none medium firm Na-caseinate Genu Pectin and smooth Type LM-18CG- gel Z 17-49 none very soft gel Supro EX 38 Tobacco pectin(undialyzed) 17-13 32960 5850 10.06 none firm gel, can Lysozyme Sigmaapple be cut, lot of pectin syneresis 17-31 10810 1173 6.893 none firm,can be Whey protein Sigma apple sliced, no isolate pectin syneresis

These results indicate that the use of pectin as the polysaccharidewithout the use of a metal ion gelation or crosslinking agent canprovide firm gels having sufficient strength to be cut, and thereforeprovides coacervation results that are as good as, or better than, thoseobtained using κ-carrageenan and a calcium lactate gelation agent. Inaddition, the use of pectin avoids the preparation of a separatecarrageenan solution, which can be viscous and difficult to handle.

In addition to preparing a polysaccharide/protein coacervate using apectin as the polysaccharide, as indicated in the examples above, it ispossible to produce a coated plant material product using a mixture ofpolysaccharides. In a particular embodiment, the polysaccharide mixturemay be a mixture of pectins, such as a mixture of tobacco pectin andanother pectin, for example a commercial pectin, e.g., Genu pectin.Alternatively, in another particular embodiment, the mixture ofpolysaccharides may include a mixture of a pectin and anotherpolysaccharide, such as a carrageenan, such as κ-carrageenan. Theadditional polysaccharide can generally be added in an amount rangingfrom about 15 to about 50 wt %, more particularly from about 30 to about50 wt %, of the total polysaccharide content of the particles.Non-limiting examples of mixtures of coacervate gel coatings ofparticles of plant material using a mixture of polysaccharides areprovided below. These materials were also subjected to the rheologicaltesting described above, and the results provided in Table 3 below.

When using more than one polysaccharide, different preparation processesare available. In one embodiment, the polysaccharides are added to theprotein-tobacco particle dispersion all at once. In another embodiment,the polysaccharides are added in a step-wise fashion. In a particularlypreferred embodiment, the polysaccharide that forms a weaker gel or thatgels less efficiently (e.g., tobacco pectin) is introduced to theprotein-tobacco particle dispersion first, and the stronger gellingpolysaccharide (e.g., κ-carrageenan or low ester pectin) is introducedsubsequently. Without wishing to be bound by any theory, it is believedthat the step-wise introduction of the polysaccharides allows the weakergelling agent to form a complex coacervate with the protein, forming aninner shell, while the stronger gelling agent forms an outer gel layer,and propagates gel formation through the bulk of the gel surrounding theparticle. Increasing the amount of more efficient gelling agent, (e.g.,κ-carrageenan, curdlan, agar, starches, cellulosics, locust bean orother gums, etc.) can have a significant effect on increasing gelstrength when the coacervate is produced by using this process.

The rheological data provided in Table 3 below suggests that thestepwise addition of gelling agents can provide increased gel strengthin the resulting coacervate while making use of polysaccharidesoriginating from tobacco. Nevertheless, it is also believed that theaddition of the polysaccharides simultaneously can permit both types ofpolysaccharide to randomly compete with each other for complexationsites with the protein, and that this may somehow increase the overallgel strength of the coacervate, as indicated in Table 3 for Samples17-62, 17-63, and 17-89. In addition, mixing the polysaccharides withthe protein-tobacco particle suspension all at once can provide handlingadvantages, since the need to make and handle the viscous carrageenansolution separately is avoided.

Irrespective of the particular process used, the incorporation of a moreefficient gelling agent with pectins that may be otherwise too low inmolecular weight or have an insufficient degree of esterification canallow these pectins to be used effectively in a coacervate coating ofprotein-coated plant particles. In particular, the processes describedherein can improve the gelation of tobacco pectin or other pectin havinga lower molecular weight by the addition of a second polysaccharide inan amount ranging between about 15 wt % and about 50 wt %, moreparticularly between about 30 wt % and about 50 wt %, of the totalcarbohydrate content.

EXAMPLE 13

A soy isolate/pectin coacervate gel encapsulated tobacco powder wasprepared by dispersing in 91 g of deionized water 0.91 g of soy isolate(Solae company, Supro EX 38) as the protein, using a high shearSilverson mixer. 6.4 g of 400 mesh pasteurized ground burley tobacco wasthen dispersed into the protein mixture using the high shear mixer. 5.7g of 0.5 M citric acid solution (Sigma, 99% pure) was then added toadjust the pH of the mixture to 4.2. 1.82 g of tobacco sourced pectin(undialyzed) as the polysaccharide was added slowly to deionized waterheated to a temperature of 70-85° C. with continuous stirring, until allof the pectin was dissolved. The resulting pectin solution was thenadded to the protein-tobacco dispersion under high shear for over 20minutes. The temperature of the dispersion was allowed to equilibratewith a water bath at 70-90° C. for 1-3 hours. 1 g of 0.153 M calciumlactate solution (Sigma, 90%) was then added, and the resultingdispersion was removed from the water bath and refrigerated for 24hours. The resulting gel dispersion was homogenized with deionized waterand then spray dried using a spray drier having an inlet temperature of200° C. and an outlet temperature of 110° C. The resulting encapsulatedparticles were collected in a sample collector, and designated Sample17-60 in Table 3 below.

EXAMPLE 14

A soy isolate/tobacco pectin/carrageenan coacervate gel encapsulatedtobacco powder was prepared by following the procedure described abovefor Example 13, with the following variations. 8.96 g of 0.5 M citricacid solution (Sigma, 99% pure) was used to adjust the pH to 4.2. 1.27 gof tobacco sourced pectin (undialyzed) was added to deionized waterheated to a temperature of 70-85° C. with continuous stirring. Heatingwas continued until the pectin was dissolved. 0.55 g of κ-carrageenan(FMC Biopolymers Gelcarin 911 NF) was added slowly to the pectinsolution with heating. This combination was then added to the soyisolate-tobacco dispersion under high shear over 20 minutes. Thetemperature of the dispersion was allowed to equilibrate with a waterbath at 70-90° C. for 1-3 hours. The dispersion was then removed fromthe bath, and 0.08 g of 0.5 M KCl (ACS grade, Fisher) solution and 1 gof 0.153 M Calcium lactate solution (Sigma, 90%) were added, and theresulting solution was refrigerated for 24 hours. The resulting gel washomogenized with excess deionized water and spray dried using a spraydrier having an inlet temperature of 200° C. and an outlet temperatureof 110° C. The resulting encapsulated particles were collected in asample collector, and designated Sample 17-62D in Table 3 below.

EXAMPLE 15

A soy isolate/tobacco pectin/carrageenan coacervate gel encapsulatedtobacco powder was prepared by following the procedure described abovein Example 14, with the following variations. The tobacco sourced pectinwas first dissolved in deionized water, this solution was added to theprotein-tobacco dispersion under high shear mixing for 20 minutes, andequilibrated with a water bath at 60-90° C. for 1-3 hours. Theκ-carrageenan was added, mixed in, and the resulting dispersion wasallowed to equilibrate in a water bath at 60-90° C. for 1-3 hours. Thebatch was removed from the water bath, and the KCl and calcium lactateadded, the resulting dispersion was refrigerated for 24 hours, and theresulting gel homogenized, spray dried, and collected, as describedabove for Example 14. The resulting material was designated Sample17-62B in Table 3 below.

EXAMPLE 16

A soy isolate/tobacco pectin/carrageenan coacervate gel encapsulatedtobacco powder was prepared by following the procedure described inExample 15, with the following variations. 0.91 g of tobacco sourcedpectin (undialyzed) and 0.91 g of κ-carrageenan (FMC BiopolymersGelcarin 911 NF) were used. The resulting material was designated Sample17-63B in Table 3 below.

EXAMPLE 17

A soy isolate/tobacco pectin/carrageenan coacervate gel encapsulatedtobacco powder was prepared by following the procedures described abovein Example 14, with the following variations. 0.91 g of tobacco sourcedpectin (undialyzed) and 0.91 g of κ-carrageenan (FMC BiopolymersGelcarin 911 NF) were used. The resulting material was designated Sample17-63D in Table 3 below.

EXAMPLE 18

A soy isolate/tobacco pectin/commercial pectin coacervate gelencapsulated tobacco powder was prepared by following the proceduresdescribed above for Example 14, with the following variations. 0.91 g oflow ester (˜40%) pectin (Genu pectin LM18 CG-Z from CP Kelco,non-standardized) was used in place of the κ-carrageenan, and the 0.5 MKCl was not used. The resulting material was designated Sample 17-89 inTable 3 below.

EXAMPLE 19

A soy isolate/tobacco pectin/commercial pectin coacervate gelencapsulated tobacco powder was prepared by following the proceduresdescribed above for Example 15, with the following variations. 0.91 g oflow ester (˜40%) pectin (Genu pectin LM18 CG-Z from CP Kelco,non-standardized) was used instead of κ-carrageenan, and the 0.5 M KClwas not used. The resulting material was designated Sample 17-88D inTable 3 below.

EXAMPLE 20

A soy isolate/tobacco pectin/commercial pectin coacervate gelencapsulated tobacco powder was prepared by following the proceduresdescribed above for Example 15, with the following variations. Thecalcium lactate salt was not added. The resulting material wasdesignated Sample 17-88E in Table 3 below.

TABLE 3 Rheological Data on Protein-Carbohydrate Coacervate Gels at 1Hz, 0.1% Strain Sample Ca # G′ (GPa) G″ (GPa) δ salt (g) Visualobservations Carbohydrate 17-92 33770 2993.3 5.063 0.32 Firm gel thatcan be cut κ-carrageenan 17-60 6341 1034 9.259 1 Very soft gel, cannotbe 100% tobacco cut without collapsing pectin (unwashed) 17-61 3419504.5 8.395 1 Soft, smooth, custard- 85% tobacco like gel; improvedpectin strength over gel made (unwashed), 15% from 100% tobaccoκ-carrageenan pectin 17-62 7048 877.7 7.099 1 Medium hardness gel 70%tobacco which can be cut; ; pectin polysaccharides mixed (unwashed), 30%together before adding κ-carrageenan to protein tobacco dispersion17-62B 12427 1466 6.725 1 Medium hardness gel 70% tobacco which can becut pectin without collapsing; first (unwashed), 30% polysaccharideadded κ-carrageenan to protein tobacco dispersion, second polysaccharideadded later. 17-62D 11053 1331 6.855 1 Medium hardness gel 70% tobaccowhich can be cut pectin without collapsing; (unwashed), 30%polysaccharides mixed κ-carrageenan together before adding to proteintobacco dispersion 17-63 9782 1116 6.507 1 Firm gel that can be cut 50%tobacco without collapsing; pectin polysaccharides mixed (unwashed), 50%together before adding κ-carrageenan to protein tobacco dispersion17-63D 19783 2104 6.087 1 Firm gel that can be cut 50% tobacco withoutcollapsing; pectin polysaccharides mixed (unwashed), 50% together beforeadding κ-carrageenan to protein tobacco dispersion 17-63B 26700 2825.336.192 1 Firm gel that can be cut 50% tobacco without collapsing; firstpectin polysaccharide added (unwashed), 50% to protein tobaccoκ-carrageenan dispersion, second polysaccharide added later 17-87 1 Verysoft gel that cannot 85% tobacco be cut without pectin collapsing(unwashed), 15% Genu pectin LM 18-CG-Z 17-88 1 Very soft gel that cannot70% tobacco be cut without pectin collapsing; (unwashed), 30%polysaccharides mixed Genu pectin LM together before adding 18-CG-Z toprotein tobacco dispersion 17-88D 3552.5 484.85 7.764 1 Soft fragile gelbut can 50% tobacco 5 be cut without pectin collapsing; first(unwashed), 50% polysaccharide added Genu pectin LM to protein tobacco18-CG-Z dispersion, second polysaccharide added later 17-88E 3508 463.67.477 None Soft fragile gel but can 50% tobacco be cut without pectincollapsing; first (unwashed), 50% polysaccharide added Genu pectin LM toprotein tobacco 18-CG-Z dispersion, second polysaccharide added later17-89 1 Very soft gel that cannot 50% tobacco be cut without pectincollapsing; (unwashed), 50% polysaccharides mixed Genu pectin LMtogether before adding 18-CG-Z to protein tobacco dispersion 17-90 101641049.8 5.854 1 Very smooth gel of 50% Sigma medium firmness that applepectin, can be cut without 50% κ- collapsing carrageenan 17-91 82271051.5 7.286 None Gel of medium firmness 50% Sigma (but less firm than17- apple pectin, 90), and that can be cut 50% Genu pectin withoutcollapsing LM 18-CG-Z

Higher molecular weight pectins, such as Sigma apple pectin, tend toform gels of high to medium strength when combined with polysaccharidessuch as carrageenans. Mixed polysaccharide systems containing tobaccopectin and κ-carrageenan, or tobacco pectin and alginate, or tobaccopectin and gellan gum, or tobacco pectin and agar, or tobacco pectin andcurdlan tend to provide better gelling coacervates than do systemscontaining tobacco pectin and other commercial pectins, or systemscontaining commercial pectins and carrageenans. For example, Samples17-62 and 17-63 (using tobacco pectin/κ-carrageenan) provided improvedresults, in terms of gel strength and sensory perception, compared toSamples 17-87, 17-88, and 17-89, which contained tobacco pectin andcommercial pectin.

Mixed polysaccharide complex coacervate gelation differed from simplebiopolymer gelation, such as simple pectin gelation, in that an optimumvalue or range for ionic strength appears to result from competingmechanisms of coacervate formation under low ionic strength and pectingelation in the presence of relatively higher concentrations of calciumsalts. As a result, increasing ionic strength by adding more salt(beyond about 0.08 to about 0.3 g 0.5 M KCl and 1-5 g of 0.153 M calciumlactate per approximately 100 ml, as used in the Examples) does notnecessarily lead to an improvement in gel strength.

A strong coacervate gel provides good encapsulation efficiency, which inturn provides an enhanced ability to form products such as compressedtobacco tablets made from such encapsulated powders, as indicated in thefollowing examples.

EXAMPLE 21

Raw, uncoated tobacco particles, without any binders were pressed in atablet press into round disc tablets of 250 mg and having a diameter of13 mm. Disintegration studies were conducted in a Sotax DT2disintegration unit, consisting of two basket-rack assemblies, two 1000ml beakers containing deionized water. The water was heated to roughly37±2° C. in order to approximate the body temperature of a consumer ofthe tablet. A tablet was placed into each of six tubes in the basket,immersed in the water, and observed visually for disintegration intosmaller pieces which can pass through the 10 mesh screen of the basketassembly. Complete disintegration was deemed to have been achieved whenany residue of the tablet remaining on the screen was a soft mass havingno palpably firm core. The results of the study are provided below inTable 4

EXAMPLE 22

The procedures of Example 21 were followed, with the followingvariations. The tablets were formed from tobacco particles coated withsoy protein and κ-carrageenan and crosslinked with KCl and calciumlactate, having a tobacco content of about 63% by weight. The resultsare provided below in Table 4.

EXAMPLE 23

The procedures of Example 21 were followed, with the followingvariations. The tablets were formed from tobacco particles coated withsoy protein and κ-carrageenan and crosslinked with calcium lactate,having a tobacco content of about 65.9% by weight. The results areprovided below in Table 4.

EXAMPLE 24

The procedures of Example 21 were followed, with the followingvariations. The tablets were formed from tobacco particles coated withsoy protein and tobacco pectin and crosslinked with calcium lactate,having a tobacco content of about 66% by weight. The results areprovided below in Table 4.

EXAMPLE 25

The procedures of Example 21 were followed, with the followingvariations. The tablets were formed from tobacco particles coated withsoy protein and a polysaccharide mixture of 50% tobacco pectin and 50%κ-carrageenan, and crosslinked with calcium lactate, having a tobaccocontent of about 65.4% by weight. The results are provided below inTable 4.

TABLE 4 Avg. % rel. Tobacco Ex disint. Std. std. content Poly- G′ G″ #time (m:ss) dev. dev. # reps. (wt %) Protein saccharide (Pa) (Pa) 2106:18 00:33 8.6 12 100 None None 22 13:07 00:57 7.2 9 63 Soyκ-carrageenan 24770 2256 protein 23 12:50 01:20 10.5 12 65.9 Soyκ-carrageenan 33770 2993 protein 24  4:59 00:14 4.6 9 66 Soy tobaccopectin 6341 1034 protein 25 10:49 00:58 9.0 12 65.4 Soy 50% tobacco26700 2825 protein pectin, 50% κ- carrageenan

Tablets made from raw, uncoated tobacco particles and particles coatedwith a protein and tobacco pectin coacervate have shorter disintegrationtimes (typically around 5-6 minutes). Tablets made with tobaccoparticles coated with a protein and κ-carrageenan coacervate have longerdisintegration times (typically around 12-13 minutes). Tablets coatedwith a protein and tobacco pectin/κ-carrageenan coacervate haddisintegration times of around 10 minutes. This illustrates thatinclusion of tobacco pectin in the encapsulating gel still provides adisintegration time on the order of that obtained for a protein andκ-carrageenan coacervate, allowing the use of tobacco derived pectin inthe preparation of coated tobacco particles.

In addition to preparation as tablets, as described above, the coatedparticles described herein may be incorporated into a variety ofproducts, in particular, smokeless products containing tobacco ortobacco substitutes, and it will be understood that the tobaccoparticles used herein can, in whole or in part, be replaced by particlesof plant material suitable as a tobacco substitute. Examples ofsmokeless products wherein the disclosed coated particles can be usedinclude pouched products, snuff, snus, and the like. The particles canbe pressed into shaped forms with or without an acceptable binder, orcan be introduced in loose form, e.g., within a pouch wrapper ormembrane. The coacervate coating can provide delayed release of theflavor of the plant material, desirably tobacco flavor, and be varied inthickness to provide a flavor release profile over time. For example,thin or uncoated particles can be mixed with particles having arelatively thin coating, particles having a coating of intermediatethickness, and particles having a thicker coating, in order to provideimmediate, short term, and longer term release of the flavor of theplant material.

While various methods and products have been described herein withreference to specific embodiments, variations and modifications may bemade without departing from the spirit and the scope of the appendedclaims. Such variations and modifications are to be considered withinthe purview and scope of the invention as defined by the appendedclaims.

1. A process for preparing coated particles of a plant material, comprising: (a) combining particles of plant material with one or more proteins in a liquid medium, under conditions effective to adsorb the protein onto at least a portion of a surface of the particles to form a first layer; and (b) mixing one or more polysaccharide compositions comprising a pectin with the liquid medium under conditions effective to adsorb at least some of the pectin onto at least a portion of a surface of the first layer to form a second layer, to form a coacervate of coated particles of plant material and a depleted liquid medium.
 2. The process of claim 1, further comprising preparing said particles of plant material by: (i) preparing an extract from a plant or part thereof, wherein said particles of plant material comprise the extract; or (ii) finely dividing a plant or a part of a plant.
 3. The process of claim 1, wherein: (i) said one or more proteins comprises at least one protein selected from the group consisting of milk protein, whey protein, soy protein, wheat protein, rice protein, egg white protein, protein obtained from tobacco, gelatin, and protein hydrolyzates; and/or (ii) said one or more proteins comprises a Zwitterionic or positively charged protein.
 4. The process of claim 1, wherein: (i) said pectin comprises at least one pectin obtained from tobacco, apples, citrus peel, plums, or gooseberries; (ii) said one or more polysaccharide composition further comprises an anionic polysaccharide; (iii) said one or more polysaccharide compositions further comprises at least one material selected from the group consisting of carrageenans, gum arabic, carboxymethyl cellulose, sodium alginates, gum tragacanth, locust bean gum, gellan gum, and xanthan gum; or (iv) two or more of (i), (ii), and (iii).
 5. The process of claim 1, wherein said process is performed without addition of a salt as a crosslinking agent.
 6. The process of claim 1, wherein said coated particles of plant material comprise κ-carrageenan in an amount from about 10% to about 60% by weight of total polysaccharides in said first and second layers.
 7. The process of claim 6, further comprising adsorbing at least some of said κ-carrageenan onto at least a portion of a surface of the second layer to form a third layer.
 8. The process of claim 1, wherein said pectin is mixed with the liquid medium prior to mixing a second polysaccharide with the liquid medium.
 9. The process of claim 1, wherein said pectin has a Huggins coefficient of between about 0.6 and 0.9.
 10. The process of claim 1, wherein: (i) said coated particles have a 8 of from about 5 to about 11, and/or (ii) said coated particles have a G′ of from about 10,000 Pa to about 35,000 Pa.
 11. The process of claim 1, further comprising (c) drying said coated particles by removing at least a portion of said depleted liquid medium.
 12. The process of claim 1, wherein said plant material comprises a tobacco, a tobacco substitute, or a mixture thereof.
 13. The process of claim 1, further comprising inducing gelation by (i) adjusting a pH of said liquid medium; (ii) adding monovalent, divalent, or trivalent cations to said liquid medium; (iii) heating to a temperature of between about 60° C. and about 90° C. for about 1 to about 3 hours; (iv) cooling to a temperature of between about 20° C. and about 0° C. for about 1 to about 48 hours; or (v) two or more of the above.
 14. A coated particle of plant material, comprising: a base particle of plant material; a first layer at least partially coating the base particle, the first layer comprising a protein; and a second layer at least partially coating the first layer, the second layer comprising a polysaccharide composition including a pectin.
 15. The coated particle of claim 14, wherein the base particle comprises: (i) a plant extract, or (ii) a finely divided plant or part of a plant.
 16. The coated particle of claim 14, wherein, said polysaccharide composition comprises a second polysaccharide and said pectin comprises a pectin derived from tobacco.
 17. The coated particle of claim 14, wherein: (i) said base particle has a largest dimension of less than about 3 mm; (ii) said coated particle comprises: (a) plant material in an amount of about 10 to about 90% by dry weight, (b) first layer in an amount of about 1% to about 20% by dry weight, and/or (c) second layer in an amount of about 5% to about 50% by dry weight; (iii) the coated base particle has a moisture content of less than about 15% by weight; (iv) the coated particle has a net negative or neutral charge; or (v) combinations of two or more of (i) to (iv).
 18. The coated particle of claim 14, wherein the plant material comprises tobacco, a tobacco substitute, or a combination thereof.
 19. A palatable or comestible product comprising at least one coated particle according to claim
 14. 20. The palatable or comestible product of claim 19, wherein said product is in a form of a tablet, stick, strip, snus, pouched product, chewable gum, spongy material, or combination thereof. 